Synthesis, crystal structure and thermodynamic properties of two transition metal coordination polymers

Abstract

Two transition metal coordination polymers (CPs) named Cd(tda)·(phen) (1) and [Zn(tda)·(phen)]·H2O (2) were synthesized through the solvothermal method with thiophene-2,5-dicarboxylic acid (H2tda) and 1,10-phenanthroline (1,10-phen) as ligands and characterized by FT-IR, DSC, XRD, etc. The crystal XRD results indicate that both CPs belong to monoclinic systems with P21/c and P21/n space groups, respectively. The structures of two 1D CPs have hydrogen bonded three-dimensional frameworks. The thermal decomposition characteristics were investigated by thermogravimetric analyses. Moreover, the molar heat capacities of two CPs were measured by temperature modulated differential scanning calorimetry (TMDSC) in the temperature range from 198 to 368 K. The calculated heat capacities of Cd-CP and Zn-CP at 298.15 K are 354.20 and 427.48 J mol−1 K-1, respectively. The thermodynamic parameters such as entropy and enthalpy relative to reference temperature 298.15 K were derived based on the molar heat capacity data.